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IFCONFIG(8)		   Linux Programmer's Manual		   IFCONFIG(8)

       ifconfig - configure a network interface

       ifconfig [-v] [-a] [-s] [interface]
       ifconfig [-v] interface [aftype] options | address ...

       Ifconfig	 is  used to configure the kernel-resident network interfaces.
       It is used at boot time to set up interfaces as necessary.  After that,
       it  is  usually	only  needed  when  debugging or when system tuning is

       If no arguments are given, ifconfig displays the	 status	 of  the  cur‐
       rently  active interfaces.  If a single interface argument is given, it
       displays the status of the given interface only; if a single  -a	 argu‐
       ment  is	 given,	 it  displays the status of all interfaces, even those
       that are down.  Otherwise, it configures an interface.

Address Families
       If the first argument after the interface name  is  recognized  as  the
       name  of	 a  supported  address family, that address family is used for
       decoding and displaying all protocol  addresses.	  Currently  supported
       address	families  include  inet	 (TCP/IP, default), inet6 (IPv6), ax25
       (AMPR Packet Radio), ddp (Appletalk Phase  2),  ipx  (Novell  IPX)  and
       netrom (AMPR Packet radio).

       -a     display  all  interfaces	which are currently available, even if

       -s     display a short list (like netstat -i)

       -v     be more verbose for some error conditions

	      The name of the interface.  This is usually a driver  name  fol‐
	      lowed  by a unit number, for example eth0 for the first Ethernet
	      interface. If your kernel supports  alias	 interfaces,  you  can
	      specify  them  with  eth0:0 for the first alias of eth0. You can
	      use them to assign a second address. To delete an	 alias	inter‐
	      face use ifconfig eth0:0 down.  Note: for every scope (i.e. same
	      net with address/netmask combination) all aliases	 are  deleted,
	      if you delete the first (primary).

       up     This  flag  causes the interface to be activated.	 It is implic‐
	      itly specified if an address is assigned to the interface.

       down   This flag causes the driver for this interface to be shut down.

       [-]arp Enable or disable the use of the ARP protocol on this interface.

	      Enable or disable the promiscuous mode  of  the  interface.   If
	      selected,	 all  packets  on  the network will be received by the

	      Enable or disable all-multicast mode.  If selected,  all	multi‐
	      cast packets on the network will be received by the interface.

       metric N
	      This parameter sets the interface metric.

       mtu N  This parameter sets the Maximum Transfer Unit (MTU) of an inter‐

       dstaddr addr
	      Set the remote IP address for a  point-to-point  link  (such  as
	      PPP).  This keyword is now obsolete; use the pointopoint keyword

       netmask addr
	      Set the IP network mask for this interface.  This value defaults
	      to  the  usual class A, B or C network mask (as derived from the
	      interface IP address), but it can be set to any value.

       add addr/prefixlen
	      Add an IPv6 address to an interface.

       del addr/prefixlen
	      Remove an IPv6 address from an interface.

       tunnel aa.bb.cc.dd
	      Create a new SIT (IPv6-in-IPv4) device, tunnelling to the	 given

       irq addr
	      Set the interrupt line used by this device.  Not all devices can
	      dynamically change their IRQ setting.

       io_addr addr
	      Set the start address in I/O space for this device.

       mem_start addr
	      Set the start address for shared memory  used  by	 this  device.
	      Only a few devices need this.

       media type
	      Set  the	physical port or medium type to be used by the device.
	      Not all devices can change this setting, and those that can vary
	      in  what	values	they  support.	 Typical  values  for type are
	      10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps Ethernet),
	      AUI  (external  transceiver) and so on.  The special medium type
	      of auto can be used to tell the driver to auto-sense the	media.
	      Again, not all drivers can do this.

       [-]broadcast [addr]
	      If  the  address	argument  is given, set the protocol broadcast
	      address for this	interface.   Otherwise,	 set  (or  clear)  the
	      IFF_BROADCAST flag for the interface.

       [-]pointopoint [addr]
	      This  keyword  enables  the point-to-point mode of an interface,
	      meaning that it is a  direct  link  between  two	machines  with
	      nobody else listening on it.
	      If  the address argument is also given, set the protocol address
	      of the other side of the link, just like	the  obsolete  dstaddr
	      keyword  does.  Otherwise, set or clear the IFF_POINTOPOINT flag
	      for the interface.

       hw class address
	      Set the hardware address of this interface, if the device driver
	      supports	this  operation.   The keyword must be followed by the
	      name of the hardware class and the printable ASCII equivalent of
	      the  hardware  address.	Hardware  classes  currently supported
	      include ether (Ethernet), ax25 (AMPR AX.25), ARCnet  and	netrom
	      (AMPR NET/ROM).

	      Set  the	multicast  flag on the interface. This should not nor‐
	      mally be needed as the drivers  set  the	flag  correctly	 them‐

	      The IP address to be assigned to this interface.

       txqueuelen length
	      Set the length of the transmit queue of the device. It is useful
	      to set this to small values  for	slower	devices	 with  a  high
	      latency  (modem links, ISDN) to prevent fast bulk transfers from
	      disturbing interactive traffic like telnet too much.

       Since kernel release 2.2 there are no explicit interface statistics for
       alias  interfaces  anymore.  The	 statistics  printed  for the original
       address are shared with all alias addresses on the same device. If  you
       want  per-address  statistics  you should add explicit accounting rules
       for the address using the ipchains(8) or iptables(8) command.

       Interrupt problems with Ethernet device drivers fail with EAGAIN (SIOC‐
       SIIFLAGS:  Resource temporarily unavailable) it is most likely a inter‐
       rupt conflict.  See  http://www.scyld.com/expert/irq-conflict.html  for
       more information.


       While  appletalk DDP and IPX addresses will be displayed they cannot be
       altered by this command.

       route(8),  netstat(8),  arp(8),	rarp(8),   ipchains(8),	  iptables(8),
       ifup(8), interfaces(5).
       http://physics.nist.gov/cuu/Units/binary.html  -	 Prefixes  for	binary

       Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
       Alan Cox, <Alan.Cox@linux.org>
       Phil Blundell, <Philip.Blundell@pobox.com>
       Andi Kleen
       Bernd Eckenfels, <net-tools@lina.inka.de>

net-tools			  2007-12-02			   IFCONFIG(8)

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